CARDIOVASCULAR SYSTEM

At the end of the lecture, students should be able to: Identify the components of the cardiovascular system. Describe the Heart as regards (position, chambers and

valves). Describe the Blood vessels (Arteries, Veins and

Capillaries). Describe the Portal System. Describe the Sinusoids. Describe the Functional and Anatomical end arteries. Describe the Arteriovenous Anastomosis.

Objectives

Pump : Heart.Network of

Tubes: Blood Vessels.

CONTENTS

It is a transportation system which uses the blood as the transport vehicle.

It carries oxygen, nutrients, cell wastes, hormones and many other substances vital for body homeostasis.

The force to move the blood around the body is provided by the beating Heart.

FUNCTIONS

• Is a hollow, cone shaped muscular pump that keeps circulation going on.• It is the size of

hand’s fist of the same person.• It has: • Apex,• Base.• Surfaces:

Diaphragmatic & Sternocostal. • Borders: Right,

Left, Inferior.

Heart

It lies in a centrally located partition in the thoracic cavity Known as the Middle Mediastinum between the two pleural sacs.Enclosed by a double sac of serous membrane (Pericardium).

2/3 of the heart lies to the left of median plane .

Location of the Heart

ATRIA : Two (Right & Left)Superior in position. They are the receiving

chambers.They have thin walls.The upper part of each

atrium is the Auricle. The Right Atrium

receives the venous blood coming to the heart.

Left Atrium receives arterial blood coming from the lungs.

Chambers of the Heart

The Ventricles are the inferior chambers.

They have thick walls.

They are the discharging

chambers (actual pumps).

Their contraction propels blood out of the heart into the circulation.

Chambers of the Heart

The heart has Four Valves:

Two Atrioventricular

Valves between atria & ventricles.

They allow the blood to flow in one direction from the atria to the ventricles.

Right AVV (Tricuspid)

Left AVV (Mitral)

VALVES OF THE HEART

Two Semilunar (Pulmonary & Aortic)

between the right and left ventricles respectively and the great arteries leaving the heart.

They allow the flow of blood from the ventricles to these arteries.

Arteries: Thick walled, do not

have valves.The smallest arteries

are arterioles.Veins: Thin walled.Many of them

possess valves.The smallest veins

are venules.Capillaries.

BLOOD VESSELS

They transport blood from the heart and distribute it to the various tissues of the body through their branches.

ARTERIES

It is the joining of terminal branches of the arteries.

ANASTOMOSIS

Anatomic End arteries: Vessels whose terminal

branches do not anastomose with branches of arteries

supplying adjacent areas.

Functional End arteries: The terminal branches do

anastomose with those of adjacent arteries but the anastomosis is insufficient to keep the tissue alive if one of the arteries is occluded.

END ARTERIES

VEINSThey transport

blood back to the heart.

The smaller veins (Tributries) unite to form larger veins which commonly join with one another to form Venous Plexuses.

DEEP VEINS (VENAE COMITANTES)

Two veins that accompany medium sized deep arteries

Microscopic vessels in the form of a network.

They connect the Arterioles to the Venules.

CAPILLARIES

Direct connections between the arteries and veins without the intervention of capillaries.

Found in:Tips of the Fingers

and Toes.

ARTERIOVENOUS ANASTOMOSIS

It is a system of vessels interposed between two capillary beds.

Veins leaving the gastrointestinal tract do not go direct to the heart.

They pass to the Portal Vein.

This vein enters the liver and breaks up again into veins of diminishing size which ultimately join capillary like vessels (Sinusoids).

PORTAL Circulation

Thin walled blood vessels like capillaries.

They are wider with irregular cross diameter.

They are found in:

Liver.Spleen.Bone marrow.Some endocrine

glands.

SINUSOIDS

The cardiovascular system is a transporting system. It is composed of the heart and blood vessels. The heart is cone shaped, covered by pericardium and

composed of four chambers. The blood vessels are the arteries, veins and capillaries. Arteries transport the blood from the heart. The terminal branches of the arteries can anastomose with

each other freely or be anatomic or functional end arteries. Veins transport blood back to the heart. Capillaries connect the arteries to the veins. Sinusoids are special type of capillaries. The portal system is composed of two sets of capillaries. The veins from the GIT go first to the liver through the

portal vein.

SUMMARY